Invading 3-3
For centuries, invading at 3-3 under a star point was considered greedy: you take the corner but get sealed in, donating the opponent a thick outer wall. AlphaGo overturned the verdict overnight — in the AI era the 3-3 invasion arrives as early as move five or six, because concrete corner territory balanced against outward influence turned out to be a fair trade at nearly every stage of the game. The deeper lesson is about trading rather than about the point itself: thickness is real value, territory is real value, and strong play constantly converts one into the other at the right price. Now make the invasion yourself — the 3-3 point sits directly under the star stone.
Now you invade: play the 3-3 point under the star point.
Play one of the marked points to finish this lesson.